Current mode ring trip detector
US5671272A · kind A · utility
9Cited by
6References
16Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Jan 30, 1995 |
| Grant date | Sep 23, 1997 |
| Priority date | — |
| Expiry date | Jan 30, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M19/026
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A circuit and method for sensing in current mode when a telephone has been answered in a telephone system in which an answer is indicated when a dc component of a signal across a resistor exceeds a predetermined reference current. Currents sensed at the terminals of the resistor are combined to provide a third current that includes the dc component, without attenuation of the dc component. A filter separates the dc component from the third current so that the dc component can be compared to the reference current.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.